Electrostatics Question 243
Question: In the given two tiny conducting balls of identical mass m and identical charge q hang from non-conducting threads of equal length L. Assume that q is so small that $ \tan \theta \approx \sin \theta $ , then for equilibrium x is equal to [AMU 2000]
Options:
A) $ 2N $
B) $ 6N $
C) $ 8N $
D) $ 20N $
Show Answer
Answer:
Correct Answer: D
Solution:
$ E _{x}=-\frac{dV}{dx}=-(6-8y^{2}), $
$ E _{y}=-\frac{dV}{dy}=-(-16xy-8+6z) $
$ E _{z}=-\frac{dV}{dz}=-(6y-8z) $
At origin x = y = z = 0 so,$ E _{x}=-6,E _{y}=8 $ and$ E _{z}=0 $
therefore $ E=\sqrt{E _{x}^{2}+E _{y}^{2}}=10N/C $ .
Hence force $ F=QE=2\times 10=20N $
